Hollow-fiber spinning nozzle

ABSTRACT

The invention relates to a hollow fiber spinning nozzle in which supply bores and a nozzle structure connected to these and having a mass discharge opening and a needle with a coagulation agent bore are formed in a base body. In accordance with the invention, at least two plate-shaped bodies structured by means of micro-structure technology are joined together to form the base body.

The invention relates to a hollow fiber spinning nozzle in accordance with the preamble of claim 1.

Hollow fiber spinning nozzles are already known which serve the manufacture of polymeric hollow fiber membranes. As shown in FIG. 1 in accordance with the enclosed drawing, such hollow fiber spinning nozzles 10 consist of a base body 12 made of metal into which a plurality of bores 14, 16, 18, 22 have been introduced. A tube 20 has been fitted into the bore 14 and a coagulation agent passage or a support agent passage 22 has been formed therein for the introduction of the coagulation agent or support agent. The bores 16 and 18 form mass supply passages for a polymer which is discharged via a ring passage 22 which likewise consists of a corresponding bore. Methods of customary metal working are used in the manufacture of the known hollow fiber spinning nozzles 10. It is here therefore that the nozzle structure arises by the assembly of both nozzle parts, with any irregularity, for example in the geometry of the ring space 22 totalizing from the production errors on the production of the base body 12 and the tube 20. Furthermore, possible assembly errors also occur which can likewise result in an irregularity of the geometry. Finally, the hollow fiber spinning nozzles known from the prior art cannot be reduced to any desired size.

It is therefore the object of the invention to provide hollow fiber spinning nozzles with which fine capillary membranes can also be manufactured, with the production tolerances being minimized and the manufacturing process for these hollow fiber spinning nozzles being made much cheaper.

This object is solved in accordance with the invention by the combination of the features of claim 1. A completely innovative manner of construction is thus provided for hollow fiber spinning nozzles, since the invention moves away from conventional metal working and uses methods of microstructure technology. In accordance with the invention, at least two plate-shaped bodies structured by means of microstructure technology are namely assembled to form the hollow fiber spinning nozzle. A second non-structured plate is preferably joined onto a first plate formed by means of microstructure technology in this process, with the second plate only being structured after attachment to the first plate. The plates are areally connected to one another. A plurality of advantages are opened up by the new production method. First, a substantially smaller dimensioning of the nozzle structure can be realized by means of microstructure technology. Moreover, a substantially higher precision can be realized with respect to the nozzle structure. This precision comes about in that the nozzle structure arises in one step. It is only restricted by the precision of the underlying lithography mask which is used in microstructure technology. Such lithography masks can, however, be produced extremely precisely with tolerances of 100 nm. A further advantage of the method in accordance with the invention lies in the substantially lower production costs of the spinning nozzles.

Special aspects of the invention result from the dependent claims following the main claim.

Generally, all materials of microstructure technology can naturally be used for the realization of the hollow fiber spinning nozzles in accordance with the invention, provided they can be anisotropically etched and bonded. However, mono-crystalline silicon, gallium arsenide (GaAs) or germanium can particularly advantageously be used.

In accordance with a particular embodiment of the invention, a hollow fiber spinning nozzle consists of two plates, with the mass supply passages, a mass flow homogenization zone, a coagulation agent/support agent supply bore and a needle stub being cut out in the first plate, while a nozzle structure having a mass annular gap and a needle with a coagulation agent/support agent bore being cut out in the second plate.

Alternatively, a design is also feasible in which the second plate additionally contains the mass supply passages and the mass flow homogenization zone. These elements and the needle stub are omitted on the first plate there. A particular feature of this design is that the needle of the spinning nozzle is only connected to the first plate at an end face.

These preferred aspects for a hollow fiber spinning nozzle, with which a simple capillary hollow fiber membrane can be manufactured, advantageously have the following dimensions: Thickness of the first plate: 0.250-1.500 mm Thickness of the second plate: 0.050-1.500 mm Outer diameter of the needle: 0.020-1.500 mm Length of the needle, incl. needle stub: 0.100-2.000 mm Diameter of the coagulation agent bore: 0.010-1.000 mm Length of the coagulation agent bore: 0.150-2.500 mm Outer diameter of the annular gap: 0.040-3.000 mm Length of the annular gap: 0.050-1.500 mm Height of the spinning nozzle: 0.300-3.000 mm Edge length of the spinning nozzle: 1.000-25.00 mm.

A further preferred aspect of the invention consists of three plates, with the first plate including supply passages, a homogenization zone and a needle stub with a central supply bore, a second plate which adjoins the first plate has supply passages, a homogenization zone and a further needle stub with a concentric ring passage and a needle extension, and wherein a third plate which in turn adjoins the second plate has a nozzle structure consisting of a central bore and two concentric annular gaps. Capillary membranes with co-extruded double layers can be manufactured by means of this hollow fiber spinning nozzle in accordance with the invention.

An alternative embodiment results in that the hollow fiber spinning nozzle is made up of three single plates, with the first plate having a central supply bore, a second plate adjoining the first plate having parallel supply passages and homogenization zones arranged with respect to these as well as a needle stub with a concentric ring passage and a central bore and with the third plate adjoining the second plate having a nozzle structure consisting of a central bore and two concentric annular gaps.

The outer diameter of the multi-passage hollow fiber spinning nozzle is advantageously smaller than 1 mm. The outer diameter of the multi-passage hollow fiber spinning nozzle is particularly advantageously smaller than or equal to 0.45 mm. A dialysis membrane with an inner diameter of 200-300 μm can be manufactured with this.

Further details and advantages of the invention result from the embodiments shown in the drawing. There are shown:

FIG. 1: a schematic section through a hollow fiber spinning nozzle in accordance with an embodiment in accordance with the prior art;

FIG. 2: a schematic section through a hollow fiber spinning nozzle in accordance with a first aspect of the invention;

FIG. 3: a schematic sectional representation of a hollow fiber spinning nozzle in accordance with a second embodiment of the invention, with three variants of the arrangement of the mass supply passages being shown;

FIG. 4: a partly sectioned three-dimensional representation of a hollow fiber spinning nozzle in accordance with FIG. 2; and

FIG. 5: a partly sectioned three-dimensional representation of a hollow fiber spinning nozzle in accordance with the embodiment in accordance with FIG. 3.

In FIG. 2, a hollow fiber spinning nozzle 10 in accordance with a first aspect of the invention is shown. Here, the total base body 26 is put together from two single plates 30 and 32. In the first plate 30, mass supply passages 34, a mass flow homogenization zone 36, a coagulation agent supply bore 38 and a needle stub 40 are formed by a corresponding etching process which will be described in detail later. The three-dimensional design of the hollow fiber spinning nozzle shown here in FIG. 2 results from FIG. 4. It can be seen there that the mass supply passages, i.e. the passages for the supply of the polymeric mass to be precipitated, are arranged in cross shape in the embodiment shown here. The mass flow homogenization zone 36 results as a ring space around the needle stub 40. The coagulation agent supply bore 38 is broadened in its region pointing toward the upper side, as can in particular be seen from FIG. 2.

The design of the second plate 32 can also be seen from FIGS. 2 and 4 which has a mass discharge opening 42 which directly adjoins the mass flow homogenization zone 36. This mass discharge opening or the mass annular gap 42 results, with the needle 44 with coagulation agent bore 46, in the high-precision nozzle structure 48. The embodiment shown in FIGS. 2 and 4 of mono-crystalline silicon has, for example, a thickness of the first plate of 0.4 mm, a thickness of the second plate of 0.1 mm, an outer diameter of the needle of 0.05 mm, a length of the needle including the needle stub of 0.15 mm, a diameter of the coagulation agent bore 38 in the expanded region of 0.1 mm, an outer diameter of the annular gap 42 of 0.1 mm and a length of the annular gap 42 of 0.1 mm. The height of the base body 26, i.e. the height of the total spinning nozzle 10, accordingly amounts to 0.5 mm, while an edge length of the base body 26 of the spinning nozzle 10 amounts to 2 mm.

In the manufacture of hollow fiber spinning nozzles by means of microstructure technology, 2 round wafer disks with diameters of 100 to 300 mm are the starting point. A plurality of spinning nozzle structures are simultaneously made from these wafers. The individual hollow fiber spinning nozzles 10 are then obtained by dividing the wafers already processed. The individual split spinning nozzles can each be given a single nozzle structure, as shown here, or also a plurality of nozzle structures in one nozzle structure compound. This is achieved in that not all nozzle structures formed on the wafer are separated from one another, but that a plurality of nozzle structures together form one multi-nozzle unit which are cut out from the wafer along their outer contour.

The manufacture of the spinning nozzles 10 starts with the two-side structuring of a first wafer which accommodates the elements 34, 36, 38, 40 of the plate 30 of the spinning nozzle 10. The structures are produced with a sequence of standard lithography processes, i.e. masks of photoresist, SiO, Si—N or similar, and standard etching processes. In the standard etching processes, in particular reactive ion etching (RIE), deep reactive ion etching (DRIE) and cryo-etching should be named. Specific deep etching processes such as DRIE and cryo-etching are particularly suitable. The lithography masks for the front side and for the rear side must be optically aligned to one another. Subsequently, the second wafer, from which the second plate should be manufactured, is bonded to the correspondingly structured first wafer. In this process, all bonding methods can be used, anodic bonding, direct bonding or similar.

However, direct bonding is particularly suitable since the highest strengths are reached and thus a good hold of the needle on the first plate is ensured. In the next step, the nozzle structure 48 with the annular gap 42 and the coagulation agent bore 46 are manufactured in a two-stage etching process. In the first step, only the deeper coagulation agent bore is driven forward. In the second step, both structures are then etch finished. Said lithography processes and etching processes area again used, with the use of the deep etching process being more advisable here than in the working of the first wafer. In the final step, the individual spinning nozzles are, as already previously described, cut out of the wafer by suitable separation processes such as wafer sawing or laser working.

Further alternative aspects of the invention will be explained with reference to FIGS. 3 and 5. Here, a hollow fiber spinning nozzle 10 is shown for the manufacture of a hollow fiber co-extruded from two layers. Here, a hollow fiber spinning nozzle 10 is shown with a base body 100 consisting of three single plates 102, 104 and 106. The single plates in turn consist of mono-crystalline silicon. A supply passage 108 for the coagulation agent is cut out in the first plate. In addition, supply passages 110, 112 for a first polymer are provided which open into an associated homogenization zone 114. The homogenization zone 114 surrounds a corresponding needle stub 116.

A coagulation agent bore 118 is likewise cut out in the second plate 104 and is surrounded by a further needle stub 120 and by a ring space 122. Furthermore, further supply passages 124 are cut out in the second plate 104 with a subsequent homogenization zone 126. Finally, the third plate 106 has two annular gaps 128 and 130 for the respective polymeric materials which should be co-extruded as well as a needle 132 with a coagulation agent bore 134. In the variants of FIG. 3 a, FIG. 3 b and FIG. 3 c, the supply passages 124 are each designed differently. While the supply passage 124 for the second polymer is only provided in the second plate 104 in the embodiment in accordance with FIG. 3 a, it extends in the variant in accordance with FIG. 3 b both through the second plate 104 and through the third plate 106. In the embodiment in accordance with FIG. 3 c, the supply passage 124 for the second polymer extends through the second plate 104 and the first plate 102, as shown here in FIG. 3 c. The representation in accordance with FIG. 5 corresponds to the section in accordance with FIG. 3 a, with it becoming clear here that 8 supply passages 112 are arranged in star shape, while only 4 supply passages 124 are arranged in cross shape.

The three plates 102, 104 and 106 are in turn connected to one another to form the base body 100 by a suitable bonding process, advantageously by direct bonding. Otherwise, the manufacturing method for the hollow fiber spinning nozzle 10 in accordance with FIGS. 3 and 5 corresponds analogously to that as was already explained in detail with reference to FIGS. 2 and 4. 

1. A hollow fiber spinning nozzle in which coagulation agent/support agent passages and mass supply passages and a nozzle structure connected to these and having a mass discharge opening and a needle with a coagulation agent/support agent bore are formed in a base body, characterized in that at least two plate-shaped bodies structured by means of microstructure technology are joined together to form the base body.
 2. A hollow fiber spinning nozzle in accordance with claim 1, wherein it consists of mono-crystalline silicon, gallium arsenide (GaAs) or germanium.
 3. A hollow fiber spinning nozzle in accordance with claim 1, wherein the mass discharge opening is an annular gap.
 4. A hollow fiber spinning nozzle in accordance with claim 1, wherein it consists of two plates, with the mass supply passages, a mass flow homogenization zone, a coagulation agent/support agent supply bore and a needle stub being cut out in the first plate, while in the second plate a nozzle structure with a mass annular gap and a needle with a coagulation agent/support agent bore are cut out.
 5. A hollow fiber spinning nozzle in accordance with claim 1, wherein it consists of two plates, with a coagulation agent/support agent supply bore being cut out in the first plate, while in the second plate mass supply passages, a mass flow homogenization zone and a nozzle structure with a mass annular gap and a needle with a coagulation agent/support agent bore are cut out.
 6. A hollow fiber spinning nozzle in accordance with claim 4, wherein its individual components have the following dimensions: Thickness of the first plate: 0.250-1.500 mm Thickness of the second plate: 0.050-1.500 mm Outer diameter of the needle: 0.020-1.500 mm Length of the needle, incl. needle stub: 0.100-2.000 mm Diameter of the coagulation agent bore: 0.010-1.000 mm Length of the coagulation agent bore: 0.150-2.500 mm Outer diameter of the annular gap: 0.040-3.000 mm Length of the annular gap: 0.050-1.500 mm Height of the spinning nozzle: 0.300-3.000 mm Edge length of the spinning nozzle: 1.000-25.00 mm.
 7. A hollow fiber spinning nozzle in accordance with claim 1, wherein it consists of three plates, with the first plate including supply passages, a homogenization zone and a needle stub with a central supply bore, a second plate which adjoins the first plate having supply passages, a homogenization zone and a further needle stub with a concentric ring passage as well as a needle extension with a central bore and with a third plate which in turn adjoins the second plate, having a nozzle structure consisting of a central bore and two concentric annular gaps.
 8. A hollow fiber spinning nozzle in accordance with claim 1, wherein the base body is made up of three individual plates, with the first plate having a central supply bore, a plate adjoining the first plate having parallel supply passages and homogenization zones associated with these as well as a needle stub with a concentric ring passage and a central bore and with the third plate adjoining the second plate having a nozzle structure consisting of a central bore and two concentric annular gaps.
 9. A hollow fiber spinning nozzle in accordance with claim 7, wherein the outer diameter of the multi-passage hollow fiber spinning nozzle is smaller than 1 mm, preferably smaller than or equal to 0.45 mm. 